The effect of Dixon rings on direct contact heat transfer performance: Comparison of counter and co-current evaporation

• Published in: Applied thermal engineering 2017-05, Vol.117, p.762-772
• Main Authors: Jin, Yanchao, Hu, Runzhi, Wang, Yiping, Cui, Yong, Liu, Yun, Huang, Qunwu
• Format: Article
• Language: English
• Subjects: Co-current and counter-current flow; Comparative analysis; Direct-contact evaporation; Energy efficiency; Evaporation; Flow velocity; Fluid dynamics; Heat transfer; Heat transfer coefficients; Optimal column height; Packing; Studies; Temperature distribution; Volumetric heat transfer coefficient; Water flow; Water temperature
• ISSN: 1359-4311; 1873-5606
• DOI: 10.1016/j.applthermaleng.2017.02.054

[Display omitted] •The comparison between counter-current and co-current evaporation.•The performance of counter-current flow is better.•The packing can enhance heat transfer effectively.•The influence factors of evaporation are analyzed.•The effect of packing on heat transfer performance is analyzed. In the experiment, direct contact evaporation in both co-current and counter-current flow were compared with pentane as dispersed phase and water as continuous phase. Dixon rings were also added into the column to enhance heat transfer in those two different contact ways. Axial temperature distribution, optimal column height and volumetric heat transfer coefficient are important parameters to evaluate heat transfer performance. The influences coming from pentane flow rate, water flow rate and inlet water temperature have also been carefully studied. Compared with co-current flow, the optimal column height decreased 15–25% and but heat transfer coefficient increased in the same scale no matter with packing or not in the counter-current condition. The optimal column height was halved and heat transfer coefficient doubled with packing when other factors were the same. Both optimal height and heat transfer coefficient would decrease with the increasing inlet water temperature. Packing in the column was an effective approach to enhance heat transfer performance especially under the condition of low water temperature as well as high water flow rate.